Case

(To). To skin an animal. In the Cookery by Mrs.
Glasse is the direction, “Take your hare when it is cased, ... and make
a pudding ...” The witticism, “First catch your hare,” may possibly
have been suggested by this direction, but it is not in the Art of
Cookery made Plain and Easy.

Case-hardened

Impenetrable to all sense of honour or shame. The allusion is
to iron toughened by carbonising the surface in contact with charcoal
in a case or closed box. It is done by heat.